Added comment to clearify the use of indexes.
Added comment to clearify the use of indexes.

Added a comment about the use of negative indexes.

Task-number: 249344
Rev-by: Marius Storm-Olsen

KDE/qt,RLovelett/qt,igor-sfdc/qt-wk,RLovelett/qt,igor-sfdc/qt-wk,radekp/qt,radekp/qt,radekp/qt,radekp/qt,KDE/qt,RLovelett/qt,igor-sfdc/qt-wk,RLovelett/qt,RLovelett/qt,radekp/qt,RLovelett/qt,RLovelett/qt,igor-sfdc/qt-wk,RLovelett/qt,pruiz/wkhtmltopdf-qt,radekp/qt,radekp/qt,igor-sfdc/qt-wk,RLovelett/qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,radekp/qt,pruiz/wkhtmltopdf-qt,KDE/qt,KDE/qt,KDE/qt,igor-sfdc/qt-wk,radekp/qt,RLovelett/qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,KDE/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,KDE/qt,igor-sfdc/qt-wk,RLovelett/qt,radekp/qt,pruiz/wkhtmltopdf-qt,KDE/qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt